1. Field of the Invention
This invention relates to cooling the air going into an engine's inlet manifold and, more specifically, to cooling the air going into an inlet manifold of an internal combustion engine with a turbocharger.
2. Description of Related Art
A turbocharged engine utilizes exhaust energy to increase the engine's horsepower and efficiency. Because of the increased energy in the compressed air, or charge air, leaving the turbocharger, the charge air is at an elevated temperature. A heat exchanger such as an intercooler or after-cooler is typically used to remove heat from the compressed air before it enters the engine's intake manifold. The intercooler/after-cooler is designed to transfer heat from the charge air to a lower temperature medium such as a cooling fluid. Thus the cooled charge air temperature is dependent upon the cooling fluid temperature. Typically the engine jacket cooling fluid or a separate cooling fluid circuit is utilized as the medium to remove the charge air heat.
Unless an air to air heat exchanger is used, the temperature of a coolant is limited and is dependent upon the engine operating temperature, the engine size, the coolant thermal capacity, or the effectiveness of the cooling system. The liquid coolant temperature in most cases will be greater than the temperature of the ambient outside air. It has been proven that lower brake specific fuel consumption and lower NOx emissions can be achieved if the charge air exiting the heat exchanger and entering the combustion chamber can be maintained at the lowest possible temperature.
Therefore, it can be appreciated that an apparatus and method for reducing the temperature of the charge air is desirable.